Question 4
- How is total internal reflection achieved in a fibre optic cable?
- State an advantage of the fibre optic cable over copper cable in communications.
Observation
This question was not popular among candidates. Majority of the candidates who attempted this question (a) and (b) performed woefully. Performance was low.
The expected answers
- How Total Internal Reflection is Achieved
Light enters the cable from one end such that the angle of incidence is greater than the critical angle for the pair of media of the interface. It undergoes multiple total internal reflection until it emerges from the other end.
- Advantages of Fibre Optic Over Copper Cable
- It carries more data/signals
- It has greater bandwidth
- It is cheaper to produce
- It is lighter